I need some help! (Movie clip question)

There probably is a really simple solution to my problem, but I’m too worked up over this to think logically at the moment. I figured some fresh eyes would help!

What I want to happen:
There are two navigational buttons. One is a BALL and the other is a BONE. When you click on the BALL, a puppy comes out and rolls it away (off the screen). Afterwards, when you click on the BONE the dog will roll the BALL back onto the stage and leaves. He will then come back for the BONE.

The dog rolling the ball and grabbing the bone are separate movie clips. I don’t want them to play simultaneously. I want the ball to be rolled back into place before he comes back out to grab the bone. So, I guess essentially I want the bone movie clip to play as soon as the ball one is done.

The dilemma:
Both movie clips are playing simultaneously. He’s rolling the ball out and grabbing the bone at the same time.

Code I have at the moment:

bone_mc.onRelease = function() {
    bone_mc.onEnterFrame = function() {
        _root.dog_house_mc.play(); }
        if (_root.ball_mc._currentframe == 120) {

If I have to do something entirely different to what I have right now, I’m open for that. This is just driving me crazy! Thanks in advance!